Helminths > Trematodes > Shistosoma

Shistosoma japonicum

Shistosoma japonicum lives in blood vessels of man, and is also called blood fluke. This worm commonly live in mesenteric vein, the eggs reach to human liver and cause cirrhosis. Shistosomiasis

Morphology

1. Adult Male:10~20mm Grayish white,having a gynecophoral canal Female:12~28mm Cylindrical, Darker,slender and longer

Suckers and testes

2. Egg •Oval, slightly yellow •No operculum, having a spine on the egg shell •Miracidium

Life cycle

Adult lives in mesenteric vein, The eggs cause abscess in intestinal wall

Adult

Egg

cercaria

miracidium

Daughter sporocyst

Mother sporocyst

Snail (Oncomelania genus)

Adults in mesenteric vein

Miracidium

Cercaria

Important points Where the adults live? How do the eggs get into the lumen of cecum ? Intermediate host: Infective host: By which way the worm get into human body ? The migration routine:

Pathogenesis

Cercaria ： cercarial dermatitis Adolescent ： inflammation of blood vessels Adult ： inflammation of mesenteric vein Egg ： cause human tissue become necrotic,and form abscess, and then the abscess become fibrotic, at last cause cirrhosis. As result, portal hypertension will take place.

Eggs in human liver

Eggs in the cecum of man

Symptom 1. Acute shistosomiasis 2. Chronic shistosomiasis 3. Terminal shistosomiasis

1. Acute shistosomiasis The patients are infected with a large number of cercariae,and also infected for the first time. Manifestations: fever, cough,diarrhea, hepatic pain, enlarged lymph nodes, hepatomegaly,etc.

2. Chronic shistosomiasis The patients have been infected with few cercariae, but for many times in a long time. Manifestations ： chronic diarrhea, dysentery,hepatomegaly, splenomegaly, weight loss, anemia, emaciation, etc.

3. Terminal shistosomiasis Hepatic Cirrhosis, portal hypertension, retarded growth All symptoms and signs of cirrhosis Most of the patients have serious emaciation, anemia, having a great deal of ascites. Nutritional exhaustion, hepatic coma, secondary infection, and upper digestive tract bleeding.

Terminal shistosomiasis

Terminal shistosomiasis

Diagnosis

Epidemiology

1. Distribution Shistosomiasis is mainly prevalent in China, Japan, Philippines and Indonesia In China, this disease is found in 13 provinces along the Yangtze River valley and to the south of the Yangtze 760 000 patients in China

2. Factors for epidemic Sources of infection Water contaminated with feces Snail existence Human come into contact with polluted water Easily infected masses (paddy planter)

Treatment and prevention

1. Eradicate the sources of infection Treat patients (Praziquantel) Control of cattle,dog,pig,et al. 2. Break the transmission routine Kill snails Manage feces Improve water supply

3. Protect the easily infected masses Promote health education Avoid touching the polluted water directly (rubber boots) Realize modernization of agriculture Vaccine development

The end